1. Field of the Invention
The present invention relates to a surface treatment agent and a surface treatment method, and particularly relates to a surface treatment agent used in hydrophobization treatment of a substrate surface used in semiconductor integrated-circuit production, and a surface treatment method using this.
2. Related Art
In the production of semiconductor devices and the like, a lithography technique is applied prior to conducting processing such as etching on a substrate. With this lithography technique, a photosensitive resin composition is used to provide a photosensitive resin layer on the substrate, then this is selectively irradiated and exposed by actinic radiation, and after a developing process has been performed, the photosensitive resin layer is selectively dissolved and removed to form a resin pattern on the substrate.
Incidentally, in recent years, trends in higher integration and miniaturization of semiconductor devices have grown, and thus progress towards miniaturization and higher aspect ratios of the inorganic pattern manufactured using a resin pattern as a mask and etching processes has advanced. However, a problem has arisen of so-called pattern collapse in the meantime. This pattern collapse is a phenomenon when forming several resin patterns and inorganic patterns on a substrate in parallel, in which adjacent patterns close in so as to lean on one another, and depending on the situation, the pattern become damaged and separate from the base. If such pattern collapse occurs, the desired product will not be obtained, thereby causing a decline in the yield and reliability of the product.
This pattern collapse is known to occur when drying a cleaning liquid in a cleaning process after pattern formation, due to the surface tension of this cleaning liquid. In fact, when the cleaning liquid is removed in a drying step, stress based on the surface tension of the cleaning liquid acts between patterns, whereby pattern collapse occurs.
Consequently, there have been numerous experiments thus far to prevent pattern collapse by adding a substance to the cleaning liquid that causes the surface tension to decrease. For example, a cleaning liquid to which isopropyl alcohol, a cleaning liquid to which a fluorine-based surfactant, and the like have been proposed (for example, refer to Patent Documents 1 and 2).
In addition, although not the same as pattern collapse, in order to improve adhesion between the resin pattern, which is the mask, and the surface of the substrate to prevent a partial loss of the resin pattern by a chemical developing solution, hydrophobization treatment (silylation treatment) has been performed on the surface of substrates using hexamethyldisilazane (HMDS) (for example, refer to “Background of the Invention” of Patent Document 3).